Carbylan Therapeutics, Inc. (the “Company”) is a clinical-stage specialty pharmaceutical company focused on the development and commercialization of novel and proprietary combination therapies that address significant unmet medical needs. The Company’s initial focus is on the development of Hydros-TA, its proprietary, potentially best-in-class intra-articular injectable product candidate to treat pain associated with osteoarthritis of the knee. The Company was incorporated in the state of Delaware on March 26, 2004 as Sentrx Surgical, Inc. The name of the Company was changed to Carbylan Biosurgery, Inc. on December 14, 2005. The name of the Company was changed to Carbylan Therapeutics, Inc. on March 7, 2014.

Since commencing operations in 2004, the Company has devoted substantially all of its efforts to identifying and developing product candidates for therapeutic markets, recruiting personnel and raising capital. The Company has devoted predominantly all of its resources to the preclinical and clinical development of, and manufacturing capabilities for, Hydros-TA. The Company has never been profitable and has not yet commenced commercial operations.

At June 30, 2015, the Company had an accumulated deficit of approximately $62.0 million. The Company expects to incur increased research and development expenses during the current Phase 3 trial of Hydros-TA and when the Company initiates the second Phase 3 trial of Hydros-TA. Management’s plans with respect to these matters include utilizing a substantial portion of the Company’s capital resources and efforts in completing the development and obtaining regulatory approval for Hydros-TA and expanding the Company’s organization.

In March 2015, the Company’s board of directors and stockholders approved a 4-for-1 reverse stock split of the Company’s common and preferred stock. The Company filed an amendment to its certificate of incorporation effecting the reverse stock split on March 13, 2015. All issued and outstanding common stock, convertible preferred stock, warrants for preferred stock, options for common stock and per share amounts contained in the condensed financial statements have been retroactively adjusted to reflect this reverse stock split for all periods presented.

On April 8, 2015, the Company’s registration statement on Form S-1 (File No. 333-201278) relating to the Initial Public Offering (“IPO”) of its common stock was declared effective by the SEC. The IPO closed on April 14, 2015 at which time the Company sold 14,950,000 shares of common stock, which included 1,950,000 shares of common stock purchased by the underwriters upon the full exercise of their option to purchase additional shares of common stock. The Company received cash proceeds of approximately $66.3 million from the IPO, net of underwriting discounts and commissions and estimated IPO expenses paid by the Company.

Prior to the closing of the IPO, all outstanding shares of convertible preferred stock converted into 8,268,531 shares of common stock with the related carrying value of $39.6 million reclassified to common stock and additional paid-in capital. In addition, all convertible preferred stock warrants were converted into warrants exercisable for common stock and the convertible promissory notes were converted in to 2,287,120 shares of common stock.

On April 14, 2015, the Company filed its Amended and Restated Certificate of Incorporation, authorizing 105,000,000 shares of capital stock, including 100,000,000 shares of authorized common stock and 5,000,000 shares of authorized undesignated preferred stock.  Both the common stock and preferred stock have a par value of $0.001 per share.  There are no shares of preferred stock outstanding at June 30, 2015.

Basis of Presentation

The accompanying interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and on a basis consistent with the annual financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the periods presented. These interim financial results are not necessarily indicative of the results to be expected for the year ending December 31, 2015, or for any other future annual or interim period. The accompanying unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto included in the Company’s Prospectus filed pursuant to Rule 424(b)(4) on April 8, 2015 with the SEC (the “Prospectus”).

Use of Estimates

The preparation of the interim condensed financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, the Company evaluates its estimates, including those related to common stock, stock-based compensation expense, warrant liabilities, accruals, derivative liability, deferred tax valuation allowance and revenue recognition. Management bases its estimates on historical experience or on various other assumptions, including information received from its service providers, which it believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Risks and Uncertainties

The product candidates developed by the Company require approvals from the U.S. Food and Drug Administration (“FDA”) or foreign regulatory agencies prior to commercial sales. There can be no assurance that the Company’s current and future product candidates will receive the necessary approvals. If the Company is denied approval or approval is delayed, it may have a material adverse impact on the Company’s business and its financial statements.

The Company is subject to risks common to companies in the pharmaceutical industry with no commercial operating history, including, but not limited to, dependency on the clinical and commercial success of its product candidates, ability to obtain regulatory approval of its product candidates, the need for substantial additional financing to achieve its goals, uncertainty of broad adoption of its approved products, if any, by physicians and consumers, significant competition and untested manufacturing capabilities.

The Company expects to incur substantial operating losses for the next several years and will need to obtain additional financing in order to launch and commercialize any products or product candidates for which it receives regulatory approval. There can be no assurance that such financing will be available or will be at terms acceptable by the Company.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents. The Company invests its excess cash in money market accounts. The Company’s cash and cash equivalents are held by a single financial institution and all cash is held in the United States. Such deposits may, at times, exceed federally insured limits. The Company has not recognized any losses during the periods presented and management does not believe that the Company is exposed to significant credit risk from its cash and cash equivalents.

Segment Reporting

The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. The Company is a specialty pharmaceutical company focused on the development and commercialization of novel and proprietary combination therapies that address significant unmet medical needs. No product revenue has been generated since inception, and all assets are held in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with an original maturity date of 90 days or less on the date of purchase to be cash equivalents. The Company invests its cash in bank deposits and money market funds.

Restricted Cash

The Company is required to guarantee the credit limit on its corporate credit card with a certificate of deposit of $50,000. The balance is included as restricted cash on the accompanying interim condensed financial statements.

Beneficial Conversion Feature

From time to time, the Company may issue convertible promissory notes that have conversion prices that create an embedded beneficial conversion feature on the issuance date. A beneficial conversion feature exists on the date a convertible promissory note is issued when the fair value of the underlying common stock to which the note is convertible into is in excess of the remaining unallocated proceeds of the note after first considering the allocation of a portion of the note proceeds to the fair value of any attached equity instruments, if any related equity instruments were granted with the debt. The intrinsic value of the beneficial conversion feature is recorded as a debt discount with a corresponding amount to additional paid-in capital. The debt discount is amortized to interest expense over the term of the note using the effective interest method.

Embedded Derivatives Related to Convertible Promissory Notes

Embedded derivatives that are required to be bifurcated from the underlying debt instrument (i.e. host) are accounted for and valued as a separate financial instrument. The Company evaluated the terms and features of the convertible promissory notes issued in September 2014 and February 2015 and identified embedded derivatives requiring bifurcation and accounting at fair value because the economic and contractual characteristics of the embedded derivatives met the criteria for bifurcation and separate accounting due to the conversion features (see Note 7 for a description of the conversion features).

Fair Value of Financial Instruments

Fair value accounting is applied for all financial assets and liabilities, and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually).

Property and Equipment, Net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which are as follows:

Leasehold improvements are amortized over the lesser of their useful lives or the term of the lease. Upon sale or retirement of the assets, the cost and related accumulated depreciation are removed from the balance sheet and the resulting gain or loss is recognized in the accompanying interim condensed statement of operations and comprehensive loss in other income (expense), net. Maintenance and repairs are charged to operations as incurred.

Pre-clinical and Clinical Trial Accruals

The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites as well as estimates for the services received and efforts expended pursuant to contracts with clinical research organizations that conduct and manage preclinical and clinical trials on the Company’s behalf. If timelines or contracts are modified based upon changes in the clinical trial protocol or scope of work to be performed, the Company modifies the estimates of accrued expenses accordingly. To date, there have been no material differences from its estimates to the amount actually incurred.

Preferred Stock Warrant Liability

The Company accounts for its warrants as either equity or liabilities based upon the characteristics and provisions of each instrument. Warrants classified as derivative liabilities are recorded on the Company’s accompanying balance sheets at their fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized as increases or reductions to other income (expense), net in the statements of operations and comprehensive loss.

Research and Development Expenditures

Costs incurred to further the Company’s research and development include salaries and related employee benefits, stock-based compensation expense, costs associated with clinical studies, nonclinical research and development activities, regulatory activities, research-related overhead expenses and fees paid to external service providers and contract research and manufacturing organizations that conduct certain research and development activities on behalf of the Company.

Stock-Based Compensation

The Company maintains performance incentive plans under which incentive stock options and non-qualified stock options may be granted to employees and non-employees. The Company accounts for stock-based compensation arrangements with employees in accordance with ASC 718, Compensation — Stock Compensation. ASC 718 requires the recognition of compensation expense, using a fair value-based method, for costs related to all share-based payments including stock options.

The Company’s determination of the fair value of stock options on the date of grant utilizes the Black-Scholes option-pricing model, and is impacted by its common stock price as well as changes in assumptions regarding a number of subjective variables. These variables include, but are not limited to, expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends.

The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period), on a straight-line basis. Stock-based compensation expense recognized at fair value includes the impact of estimated forfeitures. The Company estimates future forfeitures at the date of grant and revises the estimates, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Income Taxes

The Company accounts for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

The Company accounts for uncertain tax positions in accordance with ASC 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Net Loss per Share to Common Stockholders

Basic earnings per share to common stockholders is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the periods presented.  The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options and other potentially dilutive securities using the treasury stock method unless the effect is antidilutive.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards update (“ASU”) 2014-09, “Revenue from Contracts with Customers,” requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers.  The updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method.  In July 2015, the FASB voted to defer the effective date for annual reporting periods beginning after December 15, 2017 (including interim reporting periods within those periods) and permitted early adoption of the standard, but not before the original effective date of December 15, 2016.  The Company expects to adopt the updated standard in the first quarter of fiscal 2018.  The Company has not yet selected a transition method and is currently evaluating the effect that the updated standard will have on the financial statements and related disclosures.  

In August 2014, the FASB issued ASU NO. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, or ASU 2014-15.  ASU 2014-15 requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued and provides guidance on determining when and how to disclose going concern uncertainties in the financial statements.  Certain disclosures will be required if conditions give rise to substantial doubt about an entity’s ability to continue as a going concern.  ASU 2014-15 applies to all entities and is effective for annual and interim reporting periods ending after December 15, 2016, with early adoption permitted.  The Company does not expect that the adoption of this guidance will have a material effect on its financial statements.  

The Company follows ASC 820-10, Fair Value Measurements and Disclosures, which among other things, defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows:

The Company’s investments in money market funds are measured at fair value on a recurring basis. The money market funds comply with Rule 2a-7 of the Investment Company Act of 1940 and are required to be priced and have a fair value of $1.00 net asset value per share. These money market funds are actively traded and reported daily through a variety of sources. Due to the structure and valuation required by the Investment Company Act of 1940 regarding Rule 2a-7 funds, the fair value of the money market fund investments is classified as Level 1.

The fair value of the certificates of deposit is classified as Level 2 due to the nature of a contractual restriction with a financial institution that requires the certificate of deposit to remain in place as collateral for the credit card, and therefore the ability to liquidate the investment is limited.

As of June 30, 2015, based on borrowing rates that are available to the Company for loans of similar terms and consideration of the Company’s credit risk, the carrying value of the loan payable approximates the fair value using Level 2 inputs.

There were no transfers between Level 1 and Level 2 during the periods presented.

In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3. On a recurring basis, the Company estimates the fair value of the warrant liability. The Company used the Black-Scholes option-pricing method to calculate the fair value of the warrant liability. Generally, increases or decreases in the fair value of the underlying convertible preferred stock would result in a similar impact in the fair value measurement of the warrant liability.

The fair value of the derivative of the September 2014 and February 2015 convertible promissory notes (see Note 7) was recorded as a derivative liability instrument that is measured at fair value at each reporting period. In connection with the IPO, the convertible promissory notes were converted in to shares of common stock, and the derivative liability is therefore not present at June 30, 2015.  At December 31, 2014, the Company remeasured the fair value of the derivative for the September 2014 convertible promissory notes by estimating the fair value of the convertible promissory notes with and without the conversion derivative. To calculate the fair value of the convertible promissory notes without the conversion derivative, the Company estimated the present value of the expected cash payments at an assumed discount rate. To calculate the fair value of the convertible promissory notes with the conversion feature, the Company calculated the present value of the convertible promissory notes upon conversion at an initial public offering, and the present value of the convertible promissory notes at an equity financing. The Company applied a probability of occurrence to all of the conversion scenarios and estimated a weighted value of the notes with the conversion feature. The difference between the fair value of the convertible promissory notes with and without the conversion features is the fair value of the derivative.

The following table presents the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis:

The change in the fair value of the preferred stock warrant liability is summarized below:

The following is a summary of the activity of the derivative liability for the six months ended June 30, 2015:

Property and Equipment, Net

The following table represents the components of property and equipment (in thousands):

Depreciation expense for the six months ended June 30, 2015 and 2014, was $65,000, and $20,000, respectively.

Accrued Liabilities

(in thousands)

Operating Lease

The Company leases its facilities under a noncancelable operating lease which expires on February 29, 2016. The terms of the lease agreement require the Company to provide a security deposit of $69,000. The security deposit is included in other assets on the accompanying condensed balance sheets. The Company has a sub-lease agreement with a tenant for approximately thirty-seven percent of the square footage of the corporate headquarters. Under this agreement, the Company receives $16,000 per month as rental income which is accounted for as a reduction of rent expense. The sub-lease agreement continues until February 29, 2016.

The aggregate future minimum lease payments under this operating lease are as follows:

Gross rent expense for the three months ended June 30, 2015 and 2014 was $110,000 and $107,000, respectively, and for the six months ended June 30, 2015 and 2014 was $218,000 and $213,000, respectively. The rental expense is reduced by the sublease rental income amounts of $48,000 and $47,000, respectively, for the three months ended June 30, 2015 and 2014 and $97,000 and $94,000, respectively, for the six months ended June 30, 2015 and 2014.

Indemnification

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnification. The Company’s exposure under these agreements is unknown because it involves future claims that may be made against the Company but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations No amounts associated with such indemnifications have been recorded to date.

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. There have been no contingent liabilities requiring accrual or disclosure at June 30, 2015.

In October 2011, the Company entered into a loan and security agreement (the “Loan and Security Agreement”) with a financial institution. In September 2014, the Loan and Security Agreement was amended to provide for a new loan of $4,500,000 and repayment of the outstanding principal of the loan amounts previously disbursed in February 2013 and January 2014, with the remaining proceeds of approximately $0.5 million provided to the Company. The interest rate is 3.95% per annum and the loan is repayable in thirty-six equal monthly installments, following a nine-month interest only period. The final balloon interest payment is approximately $0.6 million and is accreted over the life of the loan. Additionally, the amendment provided for an extension of the interest only period to an eighteen-month period if certain financing events or a combination of clinical trial and financing events occur. The amendment was accounted for as a modification of loans payable, and the unamortized debt discount as of the date of the modification will be amortized over the new loan period, using the effective interest rate method.  As a result of the Company’s IPO, the interest only period has been extended to April 1, 2016.

The Loan and Security Agreement contains customary representations and warranties, covenants, closing and advancing conditions, events of defaults and termination provisions. The Loan and Security Agreement provides that an event of default will occur if (1) the financial institution determines that it is the clear intention of the Company’s investors to not continue to fund the Company in the amounts and timeframe necessary to enable the Company to satisfy the Company’s financial obligations, (2) there is a material impairment in the financial institution’s security interest in the personal property that is the collateral, (3) the Company defaults in the payment of any amount payable under the agreement when due or (4) the Company breaches any negative covenant or certain affirmative covenants in the agreement (subject to a grace period in certain cases). The repayment of the loan is accelerated following the occurrence of an event of default or otherwise, which would require the Company to immediately pay an amount equal to: (i) all outstanding principal plus accrued but unpaid interest, (ii) the final payment, plus (iii) all other sums, that shall have become due and payable but have not been paid, including interest at the default rate with respect to any past due amounts. As of June 30, 2015, the Company was in compliance with all the covenants in the Loan and Security Agreement.

As discussed in Note 1, the Company has completed its IPO and believes it will be able to meet its payment obligations under the Loan and Security Agreement during the twelve months following the most recent balance sheet date. The Company has reclassed loan payments beyond twelve months to long term.

Aggregated annual payments due under the Loan and Security Agreement are as follows:

On September 29, 2014 and February 19, 2015, the Company entered into convertible note purchase agreements and issued convertible promissory notes (the “Notes”) in an aggregate principal amount of $5.0 million and $4.0 million, respectively, to several related parties that own more than 10% of the Company’s capital stock. All principal and accrued interest on the Notes was converted to the Company’s common stock upon the completion of the Company’s initial public offering in April 2015.  Upon conversion, 2,287,120 shares of common stock were issued.

The Notes provided that upon completion of an initial public offering, the Notes would automatically convert into a number of shares of the Company’s common stock equal to the quotient obtained by dividing the entire principal amount and accrued interest on the Notes by 80% of the initial public offering price per share of the Company’s common stock. The Notes bore interest at a rate of 5% per annum, compounded annually.

Due to the automatic conversion features contained in the Notes, the actual number of shares of common stock or preferred stock that would be required if a conversion of the Notes was made through the issuance of the Company’s common or preferred stock could not be predicted prior to the conversion taking place. In addition, the conversion that would occur upon a change in control of the Company met the definition of a put option and was not closely related to the debt. As a result, the automatic conversion features and put option, exclusive of the Series B conversion feature, required derivative accounting treatment and were bifurcated from the Notes and marked to market each reporting period through the statement of operations and comprehensive loss. The fair value of the automatic conversion features and put option of the Notes, exclusive of the Series B conversion feature, were recorded as a derivative liability instrument and measured at fair value at each reporting period.

As of December 31, 2014, the Company estimated the fair value of the derivative by estimating the fair value of the Notes with and without the conversion derivative. To calculate the fair value of the Notes without the conversion derivative, the Company estimated the present value of the expected cash payments at an assumed discount rate of 8.25%. To calculate the fair value of the Notes with the conversion feature, the Company calculated the present value of the Notes upon conversion at an initial public offering, and the present value of the Notes at an equity financing. The risk-free rate for the assumed discount period is estimated at 0.05% and 0.15% in the respective conversion scenarios. The risk-free rate for the assumed discount period is estimated at 0.05% and 0.12% in the respective conversion scenarios at the valuation date of December 31, 2014. The Company applied a probability of occurrence to all of the conversion scenarios associated with the derivative and estimated a weighted value of the Notes with the conversion feature. The difference between the fair value of the Notes with and without the conversion features is the derivative. The fair value of the derivative was $1,495,000 as of December 31, 2014.

Upon issuance of the February 2015 Notes, the Company calculated the derivative liability using the same methodology and assumptions as those used as of December 31, 2014 because there were not significant changes in the Company or in the operations of the Company that had occurred in that intervening time period. The additional derivative liability recorded upon issuance of the February 2015 Notes was $1,196,000.

At April 8, 2015, the Company remeasured the fair value of the derivative liability for the Notes using a methodology similar to the methodology used at December 31, 2014, with a minimal discount period. The fair value of the derivative was $2,287,000.

The Company determined that the Notes contain a beneficial conversion feature related to the conversion feature of the Notes into Series B convertible preferred stock. The beneficial conversion feature results from the difference between the fair value of the Company’s common stock at the date of issuance and the Series B Preferred Stock Conversion price of $4.8104 at the date of issuance. The beneficial conversion feature amounted to $2,275,000 for the September 2014 Notes and $158,000 for the February 2015 Notes as of the date of issuance of the respective Notes, and was recorded as a debt discount that would be amortized through the maturity date of the Notes.

At April 8, 2015, the beneficial conversion feature amounted to $202,000 for the September 2014 Notes and $158,000 for the February 2015 Notes.  The fair value of the shares issued upon conversion of the convertible promissory notes was first allocated to the beneficial conversion feature of $360,000.  

At April 8, 2015, the loss on extinguishment of the convertible promissory notes was calculated as follows:

The Company issued warrants to purchase shares of the Company’s convertible preferred stock at various times in connection with loans payable. Immediately prior to the closing of the IPO, all convertible preferred stock warrants were converted in to warrants exercisable for common stock.  The convertible preferred stock warrants outstanding as of December 31, 2014 were as follows (in thousands, except share and per share amounts):

The fair value of the convertible preferred stock warrant liability was remeasured as of each period end. As of December 31, 2014, the Company remeasured the fair value using a Black-Scholes option-pricing method with the following assumptions: a weighted average remaining life of 6.7 years, an expected volatility of 58.9%, a weighted average risk-free interest rate of 1.80% and no expected dividend. As of April 14, 2015, the Company remeasured the fair of the convertible preferred stock warrant liability using a Black-Scholes option-pricing method with the following assumptions: the Company’s IPO price of $5.00 per share, a weighted average remaining life of 6.4 years, an expected volatility of 58.3%, a weighted average risk-free interest rate of 1.51% and no expected dividend. The Company evaluated the down-round protection provisions of the warrant agreements by using a Monte Carlo simulation model and determined that the impact of such provisions was immaterial to the fair value of the warrants at the reporting dates. The assumptions are further described as follows:

Expected Time to liquidity event — The Company estimated the time to liquidity event based on management’s analysis of the business, market conditions and clinical development.

Expected Volatility — The Company estimates the expected volatility based on the average volatility for comparable publicly traded biopharmaceutical companies over a period equal to the expected time to liquidity event. When selecting the publicly traded biopharmaceutical companies, the Company selected companies with comparable characteristics to it, including enterprise value and risk profiles, and with historical share price information sufficient to meet the time to liquidity event. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Risk-Free Interest Rate — The risk-free interest rate is based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected time to the liquidity event.

Expected Dividend Rate — The Company has never paid any dividends and does not plan to pay dividends in the foreseeable future, and, therefore, used an expected dividend rate of zero in the valuation model.

On April 14, 2015, the convertible preferred stock warrants automatically converted to common stock warrants. The convertible preferred stock warrant liability was reclassified to additional paid-in capital. During June 2015, the holder of the common stock warrants exercised those warrants for 56,545 shares of common stock in a cashless exercise.  

As of June 30, 2015, the Company’s Amended and Restated Certificate of Incorporation, as amended, has authorized 100,000,000 shares of common stock at $0.001 par value.

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors, if any, subject to the preferential dividend rights of the holders of the Series A and B convertible preferred stock. As of June 30, 2015, no dividends have been declared.

Incentive stock options are granted with exercise prices not less than the estimated fair value of common stock, and non-statutory stock options may be granted with an exercise price of not less than 100% of the estimated fair value of the common stock on the date of grant. Options granted under the Plan expire no later than 10 years from the date of grant. Incentive stock options granted under the Plan vest over periods determined by the Board of Directors, generally over four years. Non-statutory stock options vest based on the terms of the individual agreement, generally from nine months to four years.

In April 2014, the Company terminated the 2004 Plan and the board of directors approved the 2014 Stock Option Plan (the 2014 Plan), authorizing 250,000 shares for issuance under the 2014 Plan. Shares underlying any outstanding stock awards or stock option grants previously awarded remain subject to the terms of the 2004 Plan. Any shares available for grant or any shares canceled or forfeited prior to vesting or exercise subsequent to the termination of the 2004 Plan became available for use under the 2014 Plan. Upon the effectiveness of the 2014 Plan, the Company ceased granting any equity awards under the 2004 Plan.

In January and February 2015, the board of directors and stockholders, respectively, approved the 2015 Equity Plan (the “2015 Equity Plan”). In connection with the April 2015 IPO, the 2014 Plan terminated and all equity-based awards are granted under the 2015 Equity Plan. Shares underlying any outstanding stock option grants previously awarded under the 2004 Plan or the 2014 Plan remain subject to the terms of such plan. Any shares available for grant or any shares canceled or forfeited prior to vesting or exercise subsequent to the termination of the 2014 Plan and 2004 Plan became available for use under the 2015 Plan. Subsequent awards will be granted under the 2015 Plan.

As of June 30, 2015, options for 30,625 shares have been issued under the 2015 Equity Plan. The maximum number of shares of the Company’s common stock that may be delivered in satisfaction of awards under the 2015 Equity Plan, including shares issuable, but not yet issued, and considering outstanding awards granted under the 2014 Plan, as well as shares available for future awards, will be 1,532,534 shares, inclusive of 750,000 shares authorized upon creation of the 2015 Plan. The number of shares available for issuance under the Company’s 2015 Equity Plan will be increased on the first day of each fiscal year beginning in 2016, by an amount equal to the least of (1) 1,200,000 shares of stock, (2) four percent (4%) of the outstanding shares of stock on the last day of the immediately preceding year. As of June 30, 2015, the Company had 1,220,181 shares issuable upon exercise of outstanding option awards.

Total stock-based compensation expense related to options and awards granted was allocated as follows (in thousands):